Coatings are employed for a number of reasons. Product coatings or industrial coatings are typically applied in a factory on a given substrate or product, such as appliances, automobiles, aircraft, and the like. Many industries, including the aircraft industry, typically employ coating systems that provide both corrosion protection and enhanced performance.
In order to improve the corrosion resistance of a metal substrate, corrosion inhibitive pigments or additives are typically used in the coatings applied to the substrate. A common corrosion inhibitive pigment is strontium chromate, which provides excellent corrosion resistance. However, in recent years there has been widespread concern over the use of chromates, as they are known to be highly toxic and carcinogenic. Furthermore, the disposal of chromate materials is becoming increasingly difficult as municipal and government regulations are becoming more stringent.
As a result, there have been attempts to produce corrosion resistant coatings by using environmentally acceptable corrosion inhibitive pigments or additives. However, these coatings are problematic in that some of the pigments or additives used are either not compatible with the paint or cause the paint to peel off the substrate. Some are actually known to accelerate the corrosion process.
Thus there is a need to provide corrosion resistant coatings that are effective, yet not based on chromates.